Field of the Invention
This invention generally relates to a shift positioning mechanism. More specifically, the present invention relates to a shift positioning mechanism that is operates a bicycle component.
Background Information
Bicycle shift operating devices are used to shift gears of a multi-speed bicycle transmission. The multi-speed bicycle transmission typically includes a chain, one or more front sprockets or gears mounted to a front crankset and a plurality of rear sprockets or gears mounted to a rear hub of a rear wheel. The front and rear shift operating devices are designed to operate gear changing devices (e.g., a derailleur or an internal hub gear mechanism) to select a desired gear ratio. A pedaling force from the rider is transferred from the front sprockets to the rear sprockets via the chain for turning the rear wheel.
Most mechanical brake/shift operating devices use control cables that connects the brake/shift operating devices to the brake devices for braking and the gear changing devices for shifting. These control cables are typically Bowden type cables with an outer case and an inner wire. For shifting, a shift lever is usually used for operating the brake device. For example, the brake lever is also used as one of the shift lever for pulling the shift cable, while a separate lever is provided for releasing the shift cable. An operating force is typically applied by one of the rider's fingers to operate the shift levers, which in turn transmits the operating force to the shift cable via a shift operating unit. In many cases, the shift operating unit has a shift cable take-up spool. The inner wire of the shift cable is attached at one end to the cable take-up spool and its other end is attached to a part of a gear changing device such as a derailleur or an internal hub gear mechanism. The inner wire of the shift cable is wrapped (pulled) or unwrapped (released) about a peripheral edge of the shift cable take-up spool of the shift operating unit to pull and release the inner wire. By rotating the cable take-up spool, the inner wire slides within the outer case to pull or release the inner wire that operates the gear changing device. In the case of road shifters (e.g., brake/shift operating devices), the shift cable is typically routed along the handlebar. Examples of brake/shift operating devices are disclosed in U.S. Pat. No. 5,400,675 to Nagano (assigned to Shimano, Inc), U.S. Pat. No. 5,257,683 to Romano (assigned to Campagnolo) and U.S. Publication Patent No. 2007-0012137 to Dal Pra' (assigned to Campagnolo).